Fabrication of a magnetic metal-organic framework/covalent organic framework composite for simultaneous magnetic solid-phase extraction of seventeen trace quinolones residues in meats

Effective capture of quinolones (QNs) in animal-derived food is a vital procedure for food safety monitoring. However, the lack of adsorption specificity and difficult to recycle in complex substrate conditions have been major problems for most of the adsorbents. In this work, a magnetic Fe3O4/MOF/COF composite (named Fe3O4@NH2-MIL-125@TpPa-SO3H) was successfully synthesized with good magnetic responsiveness and conspicuous affinity towards QNs. The Fe3O4/MOF/COF composite was used as a magnetic solid-phase extraction (MSPE) adsorbent for pretreatment and determination of QNs in meat samples. Under optimal MSPE conditions in combination with high performance liquid chromatography-quadrupole orbitrap high resolution mass spectrometer (HPLC-Q-Orbitrap HRMS), the proposed method had good linearity (R2 ≥ 0.9978) from 0.01 to 100ng g-1, low limits of detection (0.0016 to 0.0940ng g-1), good precision with relative standard deviations lower than 5.8%. This method was effectively applied to the detection of 17 QNs in the spiked pork, chicken and beef samples with satisfactory recoveries from 83.9 to 106.2%. The separation selectivity mainly due to the π-π interaction, hydrogen bonding, and electrostatic attraction between QNs and the sulfonic acid and amino functional groups of the composite. After verification, the stability and reusability of the composite meet the requirements of complex matrix sample pretreatment. The developed MSPE method based on the magnetic Fe3O4/MOF/COF composite provided an ideal sample pretreatment alternative for determining trace QNs in complex matrixes with selectivity, simplicity, rapidity, and efficiency.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in sediments from Baiyang Lake, China

The issue of polycyclic aromatic hydrocarbons (PAHs) has been an environmental focus worldwide. In this study, the contents, sources, and ecological risks of sixteen PAHs in the sediment of Baiyang Lake were estimated, and a list of priority pollutants was established. The total PAH contents ranged from 114 to 1010 ng·g-1. The composition of PAHs indicated that 4- to 6-ring PAHs predominated in the sediment samples. The diagnostic ratio analysis showed that combustion sources were predominant for PAHs in Baiyang Lake. Specifically, the positive matrix factorization model indicated that diesel engine emissions, gasoline engine emissions, wood combustion sources, and coal combustion sources contributed 22, 32, 24, and 22% of ∑PAHs, respectively. Based on the sediment quality guidelines, mean effects range median quotient, ecological risk quotient, and toxicity equivalent quotient methods, the comprehensive assessment results of PAHs in Baiyang Lake sediments indicated that the ecological risks were at medium and low levels. The priority pollutant list showed that benzo[b]fluoranthene and benzo[a]pyrene were the highest-priority pollutants and thus should be given more attention.

Efficient Spin-to-Charge Conversion via Altermagnetic Spin Splitting Effect in Antiferromagnet RuO_{2}

The relativistic spin Hall effect and inverse spin Hall effect enable the efficient generation and detection of spin current. Recently, a nonrelativistic altermagnetic spin splitting effect (ASSE) has been theoretically and experimentally reported to generate time-reversal-odd spin current with controllable spin polarization in antiferromagnet RuO_{2}. The inverse effect, electrical detection of spin current via ASSE, still remains elusive. Here we show the spin-to-charge conversion stemming from ASSE in RuO_{2} by the spin Seebeck effect measurements. Unconventionally, the spin Seebeck voltage can be detected even when the injected spin current is polarized along the directions of either the voltage channel or the thermal gradient, indicating the successful conversion of x- and z-spin polarizations into the charge current. The crystal axes-dependent conversion efficiency further demonstrates that the nontrivial spin-to-charge conversion in RuO_{2} is ascribed to ASSE, which is distinct from the magnetic or antiferromagnetic inverse spin Hall effects. Our finding not only advances the emerging research landscape of altermagnetism, but also provides a promising pathway for the spin detection.

Screening and quantification of 146 veterinary drug residues in beef and chicken using QuEChERS combined with high performance liquid chromatography-quadrupole orbitrap mass spectrometry

This work aimed to develop an integrated high-throughput screening and quantification for multi-class veterinary drug residues by HPLC-Q-Orbitrap mass spectrometry. A qualitative screening mass database of 171 veterinary drugs was created using full scanning mode, which improved the screening accuracy and scope. Beef and chicken samples were chosen to validate the quantification method at three spiked concentration levels. The quantification method of 146 veterinary drug residues was developed. After enzymatic hydrolysis, beef and chicken samples were treated using optimized QuEChERS. The calibration curves showed good linearities with correlation coefficients of 0.9921-0.9994. The recovery rates were within 52.1-138.2 % with relative standard deviations 0.4-17.7 %. The limits of detection and limits of quantification were in the range of 0.15-3.03 μg/kg and 0.5-10 μg/kg, respectively. The proposed method was demonstrated to be reliable for the simultaneous analysis of multi-class veterinary drugs. It is of significance to expand the screening scope and quantitative analysis efficiency.

Facile synthesis of triazine-based microporous organic network for high-efficient adsorption of flumequine and nadifloxacin: A comprehensive study on adsorption mechanisms and practical application potentials

Flumequine (FLU) and nadifloxacin (NAD), as emerging contaminants, have received extensive attention recently. In this study, a triazine-based microporous organic network (TMON) was synthetized and developed as an excellent adsorbent for FLU and NAD. The adsorption behavior and influence factors were investigated in both single and binary systems. Insight into the adsorption mechanisms were conducted through experiments, models, and computational studies, from macro and micro perspectives including functional groups, adsorption sites, adsorption energy and frontier molecular orbital. The results showed that the maximum adsorption capacities of TMON for FLU and NAD are 325.27 and 302.28 mg/g under 30 °C higher than records reported before. TMON exhibits the better adaptability and anti-interference ability for influence factors, leading to the preferable application effect in kinds of real water samples. TMON also shows the application potentials for the adsorption of other quinolone antibiotics and CO₂ capture. Hydrogen-bonding interaction played the most critical role compared to π-π stacking effect, π-π electron-donor-acceptor interaction, CH-π interaction, and hydrophobic interaction during the adsorption. TMON could be regarded as a promising environmental adsorbent for its large surface area, stable physical and chemical properties, excellent recyclability, and wide range of applications.

Residual levels and dietary exposure risk assessment of banned pesticides in fruits and vegetables from Chinese market based on long-term nontargeted screening by HPLC-Q-TOF/MS

The negative impact of banned pesticides is of special importance for their high toxicity. In this study, nationwide screening of banned pesticides in 37462 fruit and vegetable samples was carried out from 2012 to 2018 using a self-developed HPLC-Q-TOF/MS technique. The dietary exposure risks associated with the banned pesticides were assessed. The results showed that 66.62 % of the samples were detected at least one pesticide. Among the pesticide-positive samples, a total of 18 banned pesticides were detected in 1798 samples for 1896 times. The risk assessment revealed that 11.71 % of the positive detections exceeded the safety limits and posed an unacceptable risk, while 37.29 % of the positive detections posed acceptable risks. According to the screening and assessment results, two national maps were presented to show the total detection ratios of the banned pesticides and the unacceptable risks of dietary exposure. It should be noted that omethoate had higher residual concentration, unacceptable risk frequency and unacceptable risk proportion. This is the first nationwide comprehensive report on screening and risk assessment banned pesticides.

Prioritization of micropollutants in municipal wastewater and the joint inhibitory effects of priority organic pollutants on Vibrio qinghaiensis sp.-Q67

Treatment of wastewater in municipal wastewater treatment plants has become a major barrier to organic pollutants entering the aquatic environment. In this study, qualitative screening of organic micropollutants was conducted in a typical municipal wastewater treatment plant (MWWTP) using gas chromatography-mass spectrometry (GC-MS). The identified compounds were prioritized according to their comprehensive scores ranked by detection frequency, semi-quantitative concentration, bioaccumulation, ecotoxicity, and biodegradability. The results showed dibutyl phthalate, antioxidant 2246, methyl stearate, 2,4,6-tri‑tert-butylphenol, and dioctyl phthalate had the top five scores and were ranked as priority organic pollutants in the municipal wastewater. The individual and joint toxicity determinations of the five compounds were carried out by a bioluminescence inhibition assay using Vibrio qinghaiensis sp.-Q67 (V. qinghaiensis). The individual toxicity assay results of these pollutants on V. qinghaiensis demonstrated that the order of the acute toxicity of the five priority organic pollutants was as follows: dioctyl phthalate> dibutyl phthalate> methyl stearate> antioxidant 2246> 2,4,6-tri‑tert-butylphenol. The joint toxicity showed partial addition or antagonism among these pollutants. The prediction results of the mixed toxicity were compared between the concentration addition model and the independent action model, indicating that a single traditional prediction model could not accurately predict the mixed toxicity of different types of organic pollutants, and that a comprehensive application of model prediction could improve the accuracy of mixed toxicity prediction. This method could provide a theoretical basis for systematic screening and toxicity prediction of pollutants in wastewater.

New insight into the co-adsorption of oxytetracycline and Pb(II) using magnetic metal-organic frameworks composites in aqueous environment: co-adsorption mechanisms and application potentials

The present study aimed to investigate the co-adsorption and application of water stabilized Fe₃O₄@ZIF-8 composite with magnetic cubic crystal structure. This new material was successfully prepared by facile modification strategy and rational design, which was used for simultaneous adsorption of oxytetracycline (OTC) and Pb(II) in aqueous solution. The co-adsorption behavior and mechanism of the composite for OTC and Pb(II) were systematically investigated by characterization techniques and batch experiments, and its application potential was effectively evaluated. The results showed that the synthesized Fe₃O₄@ZIF-8 composite innovatively retained the cubic crystal structure of ZIF-8 and was successfully loaded on the surface of Fe₃O₄ particles with small particle size to form a core-shell structure. The Fe₃O₄@ZIF-8 composite possessed a large specific surface area (1722 m²/g), magnetic separation performance (13.4 emu/g), and rich functional groups. The co-adsorption of OTC and Pb(II) on Fe₃O₄@ZIF-8 had fast reaction kinetics (equilibrium within 90 min) and large adsorption capacity (310.29 mg/g and 276.06 mg/g respectively). The adsorption process for both contaminants followed pseudo-second order kinetics and Langmuir isotherm models and had synergistic and competitive effects at the same time. π-π stacking and electrostatic interaction were the main mechanisms of adsorption. Fe₃O₄@ZIF-8 had good adsorption performance after cyclic adsorption for 4 times and it performed well in the treatment of real waste water. This study provided a new sight for the control of combined pollution of OTC and Pb(II) and proved Fe₃O₄@ZIF-8 composites have great application potentials for complex wastewater treatment.

Determination of Vancomycin and Norvancomycin Residues in Milk by Automated Online Solid-Phase Extraction Combined With Liquid Chromatography-High Resolution Mass Spectrometry

Background

Vancomycin and norvancomycin, as potent antibacterial retention drugs, were used illegally on animals bred for food, which directly affected the quality and safety of animal-derived food, and even harmed human health.

Objective

A fast analysis method, which was adopted to detect residues of vancomycin and norvancomycin in milk, was implemented on a chromatographic system containing online solid-phase extraction (SPE) device that combined with high-resolution mass spectrometer (HRMS).

Method

First, the analytes were added to the blank milk sample were extracted with water [containing 0.1% trifluoroacetic acid (TFA)]–acetonitrile (ACN) (8:2, v/v), and then were purified and enriched on a C18-XL column, whereafter eluted from the purification column onto the analytical column (Shiseido Capcell Pak ADME column) for chromatographic separation prior to hybrid quadrupole–Orbitrap (Q-Orbitrap) detection.

Results

The results showed that the limit of detection (LOD) for each analyte and the limit of quantitation (LOQ) were 0.15  and 0.5 μg/kg, respectively. The correlation coefficient(s) of vancomycin and norvancomycin ranged from 0 to 200 ng/mL were greater than 0.9983.

Conclusions

These validations reflected that it was suitable for the established method to rapidly analyze vancomycin and norvancomycin residues in milk.

Highlights

The method for detecting vancomycin and norvancomycin residues in milk by online SPE combined with LC-HRMS. Online SPE technology realized automation, and the application of HRMS greatly improved the reliability of qualitative and quantitative analyses. The developed method is fast, simple, and reliable; each methodological index can meet requirements of trace analyses of vancomycin and norvancomycin in milk.

Recent advances in porous organic frameworks for sample pretreatment of pesticide and veterinary drug residues: a review

Rapid and accurate detection of pesticide and veterinary drug residues is a continuing challenge because of the complex matrix effects. Thus, appropriate sample pretreatment is a crucial step for the effective extraction of the analytes and removal of the interferences. Recently, the development of nanomaterial adsorbents has greatly promoted the innovation of food sample pretreatment approaches. Porous organic frameworks (POFs), including polymers of intrinsic microporosity, covalent organic frameworks, hyper crosslinked polymers, conjugated microporous polymers, and porous aromatic frameworks, have been widely utilized due to their tailorable skeletons and pores as well as fascinating features. This review summarizes the recent advances for POFs to be utilized in adsorption and sample preparation of pesticide and veterinary drug residues. In addition, future prospects and challenges are discussed, hoping to offer a reference for further study on POFs in sample pretreatment.

Occurrence and removal of organic pollutants by a combined analysis using GC-MS with spectral analysis and acute toxicity

The presence of xenobiotic compounds especially organic micro-pollutants in municipal wastewater treatment plant (MWWTP) is a major concern worldwide. The occurrence and removal of trace organic pollutants in a MWWTP by a combined analysis using GC-MS with spectral analysis and acute toxicity were studied in this work. Non-target screening and toxicity analysis of organic compounds were conducted to understand the types of toxic and refractory pollutants in municipal wastewater and evaluated the toxicity removal efficiency of MWWTP. The results showed that most of the effects were significantly reduced or completely eliminated during the wastewater treatment process, while some compounds, such as antioxidants, drugs, and organic plasticizers, had detection rates of up to 100% at each site, indicating that these harmful substances remained throughout wastewater treatment process. Based on Pearson correlation analysis, paired correlation analysis showed a positive correlation between UV₂₅₄, humification index, conventional parameters, and organic acute toxicity, while acute toxicity was negatively correlated with biological index and fluorescence index. The results indicated that the composition of MWWTP had a similar influence law in different locations, and the combination of spectral analysis provided a new insight to qualitatively and quantitatively showed the distribution of organic pollutants in the wastewater treatment system.

Immobilization Mechanism of Nano-Hydroxyapatite on Lead in the Ryegrass Rhizosphere Soil Under Root Confinement

The immobilization effect and mechanism of nano-hydroxyapatite(NHAP) on Pb in the ryegrass rhizosphere soil were studied by root-bag experiment. The speciation analysis results revealed that the residual Pb concentrations in the rhizosphere soil significantly increased after NHAP application. The acid-soluble and reducible Pb concentrations significantly decreased, indicating that NHAP had obviously immobilized Pb. Meanwhile, NHAP significantly promoted the secretion of tartaric acid from ryegrass roots, resulting the rhizosphere soil pH had been below that of the control group. This helped to relieve the stress of Pb on ryegrass, also promoted the dissolution of NHAP, resulting the formation of stable precipitation with more Pb ions. NHAP increased the rhizosphere soil pH by 0.03 to 0.17, which promoted the conversion of Pb to non-utilizable bioavailability. The total Pb mass balance indicated only a very small proportion Pb transferred to the shoots through ryegrass roots. The formation of pyromorphite by Pband NHAP in soil was accordingly to interpret the dominant mechanism for Pb immobilization.

Pollution characteristics of metal pollutants in PM2.5 and comparison of risk on human health in heating and non-heating seasons in Baoding, China

PM_2.5 particles were collected to study the distribution, accumulation and health risk assessment of metal pollutants. The concentrations of 11 kinds of metal elements in PM_2.5 during heating period and non-heating period were analyzed. Based on the American health risk assessment model as well as the human exposure parameters in China, the human health risk was assessed. The concentrations of metal components in PM_2.5 during the heating period were, in descending order, Pb, Mn, Cr, As, Sb, Se, Ni, Cd, Tl, Hg, and Be, while during the non-heating period, they were basically in the same order, except Cd and Ni, as the concentration of the former was a little higher than that of the latter. The concentrations of As, Cd, Hg, Ni, Se, and Tl were quite different in the heating period and non-heating period. The non-carcinogenic risks caused by metal elements were lower than the minimum acceptance 10^-6 per year during both the heating period and non-heating period. The non-carcinogenic results of a descending order were Pb, Mn, Sb, Tl, Se, and Hg. The carcinogenic risks of a descending order were Cr, As, Cd, Ni, and Be. The risks of As and Cr to children were over 10^-6. Hence, As and Cr should be considered as priorities.

Assessment of the Remediation Effect of Nano-hydroxyapatite in Exogenous Pb-contaminated Soil Using Toxicity Characteristic Leaching Procedure and Soil Enzyme Activities

Lead (Pb) is one of the most abundant metal soil pollutants. In this research, effects of nano-hydroxyapatite (NHAP) on remediation of Pb-contaminated soil were evaluated by the measure of extractable Pb using toxicity characteristic leaching procedure (TCLP) and soil enzyme activities. Results suggested NHAP significantly decreased the concentrations of extractable Pb, achieving the maximum decrement rate of 75.71%. Activity of urease decreased with increasing Pb concentrations. Moreover, activities of alkaline phosphatase, dehydrogenase, and catalase increased at the lower Pb levels and decreased at the higher Pb levels. NHAP had a positive effect on regulating soil enzymes. Thus, soil enzyme activities, especially dehydrogenase, could be used as biological indicators of Pb pollution and NHAP remediation. Moreover, NHAP could reduce the mobility and bioavailability of Pb, while increasing enzyme activities, thereby lowering the leaching risk and biotoxicity of Pb.

Influence of Nano-Hydroxyapatite on the Metal Bioavailability, Plant Metal Accumulation and Root Exudates of Ryegrass for Phytoremediation in Lead-Polluted Soil

Lead is recognized as one of the most widespread toxic metal contaminants and pervasive environmental health concerns in the environment. In this paper, the effects of nano-hydroxyapatite (NHAP) on remediation in artificially Pb-contaminated soils and ryegrass were studied in a pot experiment. The addition of NHAP decreased the water- and acid-soluble, exchangeable, and reducible fractions of Pb, extracted using the Community Bureau of Reference (BCR) method, whilst greatly increasing the residual fraction of Pb. Oxidizable Pb was increased slightly. No significant increase in soil pH was caused by the application of NHAP. Compared to conditions without NHAP, the addition of NHAP decreased the Pb content in ryegrass shoots and roots by 13.19-20.3% and 2.86-21.1%, respectively. Therefore, the application of NHAP reduced the mobility and bioavailability of Pb in the soil. In addition, the application of NHAP improved the fresh weight of shoots and roots, and promoted the growth of ryegrass. NHAP played a positive role in stimulating ryegrass to secrete tartaric acid.

Feasibility of Pb phytoextraction using nano-materials assisted ryegrass: Results of a one-year field-scale experiment

The effect of the combined application of nano-hydroxyapatite (NHAP) or nano-carbon black (NCB) on the phytoextraction of Pb by ryegrass was investigated as an enhanced remediation technique for soils by field-scale experiment. After the addition of 0.2% NHAP or NCB to the soil, temporal variation of the uptake of Pb in aboveground parts and roots were observed. Ryegrass shoot concentrations of Pb were lower with nano-materials application than without nano-materials for the first month. However, the shoot concentrations of Pb were significantly increased with nano-materials application, in particular NHAP groups. The ryegrass root concentrations of Pb were lower with nano-materials application for the first month. These results indicated that nano-materials had significant effects on stabilization of lead, especially at the beginning of the experiment. Along with the experimental proceeding, phytotoxicity was alleviated after the incorporation of nano-materials. The ryegrass biomass was significantly higher with nano-materials application. Consequently, the Pb phytoextraction potential of ryegrass significantly increased with nano-materials application compared to the gounps without nano-materials application. The total removal rates of soil Pb were higher after combined application of NHAP than NCB. NHAP is more suitable than NCB for in-situ remediation of Pb-contaminated soils. The ryegrass translocation factor exhibited a marked increase with time. It was thought that the major role of NHP and NBA might be to alleviate the Pb phytotoxicity and increase biomass of plants.

Quantification of metallothioneins in the earthworm by lomefloxacin-europium(iii) fluorescent probe

A new fluorimetric method was established for the determination of trace amounts of metallothioneins (MT) in earthworm, using a lomefloxacin-europium(iii) (LMLX-Eu(3+)) complex as a fluorescent probe. In a pH 6.5 Tris-HCl buffer solution, MT can markedly decrease the fluorescence intensity of LMLX-Eu(3+) at λ = 613 nm, and the magnitude of the decrease in this intensity was in direct proportion to the concentration of MT. The linear range was 0.08-20 mg L(-1) with a detection limit of 0.022 mg L(-1), and the recovery was in the range of 91.9-104.4%. The results show that the fluorimetric method is relatively accurate and sensitive to measurements of concentration for MT over a wide range. This method has been successfully applied to the determination of the concentration of MT induced by heavy metal ions (Cd(2+), Pb(2+), Cu(2+), Zn(2+)) in Eisenia andrei. The amount of MT increased significantly in a dose-dependent manner to the heavy-metal exposure, and these proteins can be used as biomarkers to assess the impact of heavy-metal contamination in soils. The method offered high sensitivity as well as accuracy with simple instrumentation and is suitable for direct quantification of total MT in Eisenia andrei.

Analysis of dissolved organic matters in Fu River of Baoding using three dimensional fluorescence excitation-emission matrix

The fluorescence properties of dissolved organic matter (DOM) in Fu River in Baoding were investigated by three-dimensional fluorescence spectrometry. The type, distribution and origin of the DOM were estimated on basis of the position, number and intensity of fluorescence peaks in the spectra. Two types of fluorescence peaks were detected from Fu River. There are protein-like fluorescence peaks A with Ex/Em = 225-230/340 nm and soluble microbial metabolites peaks B with Ex/Em=275/340-350 nm. The protein-like fluorescence peaks and soluble microbial metabolites peaks were founded in different times and stations in Fu River. Certain correlation was observed between the fluorescence intensity of DOM and the water quality parameters of Fu River. Good correlation of different fluorescence peaks showed the same of source. The fluorescence intensity of the two types had a significant positive relationship with COD, TN, TP and NH3-N concentration, this phenomenon indicating that the fluorescence peaks can speculate the level of pollution of Fu River. These results provided a reference for the pollution control in Fu River.

In vitro and in vivo proliferation, differentiation and migration of cardiac endothelial progenitor cells (SCA1+/CD31+ side-population cells)

BACKGROUND

Side-population (SP) cells are a select population identified by a capacity to efflux Hoechst dye and are enriched for stem/progenitor cell activity. Previous studies suggested that cardiac SP (CSP) cells could be divided into SCA1(+)/CD31(-) and SCA1(+)/CD31(+) CSP cells. SCA1(+)/CD31(-) CSP cells have been shown to be cardiac stem/progenitor cells. However, SCA1(+)/CD31(+) CSP cells have not been fully characterized.

OBJECTIVE

The aim of the present study was to characterize SCA1(+)/CD31(+) CSP cells in the adult mouse heart, and investigate their abilities to proliferate, differentiate, vascularize and migrate in vitro and in vivo.

RESULTS

Using fluorescence-activated cell sorting (FACS), RT-PCR, and assays of cell proliferation, differentiation and migration, and a murine model of myocardial infarction (MI), we showed that SCA1(+)/CD31(+) CSP cells express stem cell and endothelial-specific genes, and reside in the blood vessels. These cells were able to proliferate, differentiate, migrate and vascularize in vitro and in vivo. After MI, SDF-1α and CXCR4 were up-regulated in the damaged myocardium and on SCA1(+)/CD31(+) CSP cells, respectively. Our results further showed that SDF-1α induced migration of these cells in vitro. Importantly, we found that SCA1(+)/CD31(+) CSP cells could migrate into the ischemic region from the non-ischemic area within the myocardium and form a vascular tube-like structure after MI.

CONCLUSIONS

Based on the gene expression profile, localization of SCA1(+)/CD31(+) CSP cells, and their ability to proliferate, differentiate, migrate and vascularize in vitro and in vivo, we postulate that SCA1(+)/CD31(+) CSP cells may represent endothelial progenitor cells in the mouse heart.

Effects of repeated exposure to decabrominated diphenyl ether (BDE-209) on mice nervous system and its self repair

Decabrominated diphenyl ether (BDE-209) is widely used as brominated flame retardants (BFRs). In order to investigate its direct neurotoxic effects on mice and its self repair, mice were repeatedly exposured to BDE-209. Different concentrations of BDE-209 (0, 0.1, 40, 80 and 160mg/kgbw/d) were administered daily to CD-1 Swiss mice by gavage for 15, 30 and 60 days. Body and brain weights were recorded after the exposure. And the self repair was studied. Levels of acetylcholinesterase (TchE), superoxide dismutase (SOD) and malonic dialdehyde (MDA) in brain were analyzed. Experimental results suggested that the nervous system was permanently damaged by BDE-209 through the cholinergic system enzyme.

Development of magnetic particle-based chemiluminescence enzyme immunoassay for the detection of 17beta-estradiol in environmental water

In the present work, a simple, fast, and highly sensitive chemiluminescence enzyme immunoassay for 17beta-estradiol (E2) in environmental water samples was developed, using magnetic particles (MPs) labeled with secondary antibody as both the immobilization matrix and the separation tools. The specific anti-E2 polyclonal antibody (PcAb) was produced against a conjugate of estradiol-bovine serum albumin. The specificity of the anti-E2 antibody was studied. The results showed that the antibody did not cross-react with the structurally related endocrine-disrupting compounds, including estrone, ethinyl E2, estriol, E2-17-glucuronide, E2-3-sulfate-17-glucuronide, androstenedione, and dihydrotestosterone. The water samples were pretreated with solid-phase extraction using C18 cartridges for the removal of matrix effects. Several physicochemical parameters including the dilution ratios of E2-6-horseradish peroxidase conjugate and anti-E2 PcAb, immunoreaction time, volume of chemiluminescent substrate and MPs, chemiluminescence reaction time, and pH of assay solution were studied and optimized. At optimal experimental conditions, it was found that the proposed method exhibited high performance with detection limit of 2.0 pg/mL, linear range of 20-1,200 pg/mL, and total assay time of 45 min. Both inter- and intra-assay coefficient of variation were less than 10%. The average recoveries of three different spiked concentration samples ranged from 86.3% to 108%. The method was successfully applied to the determination of E2 in river, waste, and tap water, and showed a good correlation with the commercially available radioimmunoassay kit.

Levels and distribution of polybrominated diphenyl ethers in various tissues of foraging hens from an electronic waste recycling area in South China

Levels and distribution of polybrominated diphenyl ethers (PBDEs) in various tissues of hens foraging near an electronic wastes stack spot in Taizhou, China, were studied. With high-resolution gas chromatography/negative chemical ionization mass spectrometry analysis, 37 PBDE congeners from di- to hepta-brominated and BDE 209 were identified and quantified in the liver, heart, skin, fat, intestine, muscle, blood, oviduct, ovum, gizzard, spleen, and kidney tissues of hens. Based on lipid weight in all analyzed tissues, muscle exhibited the highest PBDE concentrations (17,977 ng/g lipid wt), BDE 209 was the dominant congener, and the sum of quantified PBDEs followed the order muscle > fat > intestine > heart > liver > oviduct > gizzard > blood > skin > ovum. Principal component analysis results indicated that the hen muscle tissue was characterized by BDE 32, 209, 28, and 75 congeners; hen intestine, heart, and blood tissues were characterized by BDE 153, 99, 183, 138, 154, 47, and 100 congeners; and hen skin, liver, oviduct, ovum, gizzard, spleen, kidney, and fat tissues had a similar PBDE congener profile. The present study also indicated that the PBDE congeners were persistent enough to accumulate through the human food chain and that deca-BDE might be potential risk to ecoenvironment.

Determination of nitrobenzene in wastewater using a hanging mercury drop electrode

The determination of trace amount nitrobenzene in wastewater on a hanging mercury drop electrode was studied. The determination conditions of pH, supporting electrolyte, accumulation potential, accumulation time, and voltammetric response were optimized. The sharp peak of the nitrobenzene was appeared at 0.05 V. The peak electric current was proportional to the concentration of nitrobenzene in the range of 1.47 x 10(-5) approximately 1.0 x 10(-3) mol/l with relative standard deviations of 3.99 approximately 8.94%. The detection limit of the nitrobenzene in water was 5 x 10(-6) mol/l. The proposed method offered low limit of determination, easy operation, the use of simple instrumentation, high sensitivity and good reproducibility. It was applied to the determination of nitrobenzene in wastewater with an average recovery of 94.0% approximately 105%. The proposed method provided fast, sensitive and sometimes real time detection of nitrobenzene.

Effective separation and simultaneous determination of seven fluoroquinolones by capillary electrophoresis with diode-array detector

A simple, rapid and accurate method has been developed for effective separation and simultaneous determination of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin residues in porcine tissue by capillary electrophoresis with diode-array detector. The separation conditions were investigated and optimized. The sample was extracted with acetonitrile, and a mixture consisted of 25 mM NaH(2)PO(4), 25 mM Na(2)B(4)O(7) and 25 mM H(3)BO(3) (pH 9.0) was used as a running buffer. A linear relationship between concentration and peak area for each compound was obtained in the concentration range of 0.5-100 mg/L with a correlation coefficient greater than 0.9994. For analysis of porcine tissue, the detection limits of lomefloxacin, gatifloxacin, enoxacin, ciprofloxacin, ofloxacin, enrofloxacin and pefloxacin were 0.013, 0.012, 0.023, 0.040, 0.037, 0.035 and 0.034 mg/kg, respectively. The recoveries are in the range of 72-93%. The intra-day precision is less than 5%, and the inter-day precision is less than 10%. The proposed method has high resolution, speed and the extremely small sample volume required. It can permit to confirm the presence of the studied seven fluoroquinolones in porcine tissue at the required maximum residue limit (MRL) level.

Determination of nitrobenzene by differential pulse voltammetry and its application in wastewater analysis

A new method for the determination of nitrobenzene (NB) by differential pulse voltammetry (DPV) based on an adsorptive stripping technique was developed. Cyclic voltammetry (CV) was used in a comparative investigation into the electrochemical reduction of NB at a glassy carbon electrode (GCE). With this electrode, the sharp peak of NB appeared at -0.71 V (vs. Ag/AgCl). The experimental parameters were optimized. Studies on the effect of pH on the peak height and peak potential were carried out over the pH range ca. 9.0-11.5 with sodium carbonate/sodium hydrogen carbonate buffer solution. A solution of pH 9.9 was chosen as analytical medium. Cathodic peak currents were found to be linearly related to the concentration of NB over the range ca. 12.3-1.23 x 10(4) microg L(-1) with relative standard deviations of ca. 3.26-6.75%. The detection limit of NB in water was 5.42 microg L(-1). The interference of organic and inorganic species on the voltammetric response was also studied. The proposed method was applied to the determination of NB in wastewater samples with an average recovery of ca. 95.9-102.4%.

[Direct determination of lead and cadmium in soil by slurry-sampling graphite furnace atomic absorption spectrometry using matrix modification technique]

A method for the direct determination of lead and cadmium in soil by slurry-sampling graphite furnace-atomic absorption spectrometry using NH4 H2 PO4 as matrix modifier was developed. The effects of slurry stability, particle size of sample, matrix modifiers, ashing temperature, atomization temperature and common coexistent components on the signal intensities of lead and cadmium were investigated. The apparent activation energies of lead and cadmium were measured based on the linear relationship between the logarithm value of atomization peak time and atomization temperature. The mechanism of matrix modification was discussed. Under optimized conditions, the detection limit was 9.05 x 10(-10) g x mL(-1) for Pb and 1.76 x 10(-11) g x mL(-1) for Cd. The recoveries were in the range of 91%-97% for Pb and 93%-109% for Cd. The relative standard deviations were in the range of 4.2%-7.8%.

[Determination of trace cadmium in environment water samples by flame atomic absorption spectrometry using flow injection on-line preconcentration with double microcolumns]

A rapid and sensitive methed for the determination of trace cadmium in environment water samples based on flowinjection on-line preconcentration on two-microcolumn system-flame atomic absorption spectrometry has been developed. The cadmium in samples was sequentially retained on two microcolumns with cation exchange resin and was eluted directly in the nebulizer by 1.5 mol x L(-1) HCl solution. The characteristic concentration (preconcentration time 1 min) for cadmium was 0.931 microg x L(-1). The relative standard deviation at the 5 microg x L(-1) level was 2.69% and the corresponding detection limit (3sigma) was 0.808 microg x L(-1). The method has been successfully applied to the determination of cadmium in water reference material GBW08608 and other water samples.

The effect of potent iron chelators on the regulation of p53: examination of the expression, localization and DNA-binding activity of p53 and the transactivation of WAF1

Iron (Fe) chelators induce a G1/S arrest and several of these are undergoing clinical trials as anticancer agents. Despite this, little is known concerning the precise function of Fe in cell cycle progression and the role of p53 in this process. The aim of this study was to assess the effect of Fe chelators on p53 and the mechanism involved in the chelator-mediated increase in mRNA levels of the universal cyclin-dependent kinase inhibitor p21CIP1/WAF1. Cells were incubated with the potent Fe chelator 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) and the results compared with those from cells treated with actinomycin D (Act D), which induces p53. Following incubation with 311, a 3- to 5-fold increase in nuclear p53 protein was observed in cells with wild-type p53. In addition, 311 increased p53 DNA-binding activity 2-fold, while Act D increased it 3- to 5-fold in cells with native p53. To determine the role of p53 in WAF1 transcription, a reporter construct was used consisting of a WAF1 promoter containing the p53-binding site. In cells with wild-type p53, chelators had no effect on luciferase activity, while the positive control, Act D, caused a significant increase. Hence, despite increased p53 protein expression and p53 DNA-binding activity following chelation, these latter results suggested it had no role in up-regulating WAF1 mRNA. Our experiments demonstrated: (i) that the elevated WAF1 mRNA expression after Fe chelation was due to increased transcription and also to a post-transcriptional mechanism that was sensitive to cycloheximide; and (ii) that Fe-chelation increased WAF1 expression through a p53-independent pathway.

Spatial distribution and developmental appearance of postjunctional P2X1 receptors on smooth muscle cells of the mouse vas deferens

P2X1-type purinoceptors have been shown to mediate fast transmission between sympathetic varicosities and smooth muscle cells in the mouse vas deferens but the spatial organization of these receptors on the smooth muscle cells remains inconclusive. Voltage clamp techniques were used to estimate the amplitudes of spontaneous excitatory junction currents (SEJCs) in cells of the vas deferens longitudinal smooth muscle layer. These currents involved the activation of about 6% of the P2X-type channels present on the cell, as compared to whole cell currents produced when isolated smooth muscle cells were exposed to maximal concentrations of either ATP or alpha,beta-MeATP. Immunofluorescence staining of the vas deferens with antibodies against P2X1 receptor showed a diffuse, grainy distribution over the entire membrane of each smooth muscle cell. Anti-P2X1 staining was not markedly clustered beneath anti-SV2-stained sympathetic varicosities. Similar results were obtained for cells in the urinary bladder. During development, P2X1 mRNA was detected as early as embryonic day 15 (E15). Increasing intensities of diffuse immunostaining for P2X1 were observed in the walls of the bladder, tail artery, and aorta from E15 until 6 weeks postnatal. The vas deferens showed increasing intensities of diffuse staining of its smooth muscle layers between 2 and 6 weeks postnatal, consistent with the time-course of development of fast purinergic transmission described previously. Together, the results suggest that the response of smooth muscle of the vas deferens to ATP released from sympathetic varicosities relies on rapidly desensitizing P2X1 receptors, distributed diffusely across the smooth muscle cell surface.

A high-grade primary leiomyosarcoma of the bladder in a survivor of retinoblastoma

Second nonocular malignancies develop with increased incidence in patients with hereditary retinoblastoma. Osteosarcoma is by far the most common type with an incidence of up to 50%, followed by soft tissue sarcomas. Visceral leiomyosarcoma is extremely rare and only 2 cases have been reported in the past 2 decades, one in the liver and another one in the urinary bladder, both of which developed after cyclophosphamide therapy. Here we report a case of vesical leiomyosarcoma that was diagnosed in a 49-year-old woman 47 years after the diagnosis of a hereditary retinoblastoma. The patient's retinoblastoma was treated with unilateral enucleation without adjuvant radiation or chemotherapy. We believe that this is the first report of vesical leiomyosarcoma occurring in a patient with retinoblastoma without a prior history of radiation or chemotherapy. This report is significant not only because of the rarity of vesical leiomyosarcoma as a second nonocular tumor in retinoblastoma patients, but also because of the infrequency of vesical leiomyosarcoma in general. We also investigated the potential molecular pathogenesis of the leiomyosarcoma.

Structure and chromosome location of the mouse P2X(1) purinoceptor gene (P2rx1)

P2X(1) receptors are ATP-gated cation channels that mediate the fast, purinergic component of sympathetic nerve-smooth muscle neurotransmission in the mouse vas deferens and may serve comparable functions in the urinary bladder and the arteries. The gene for mouse P2X(1) (P2rx1) was cloned and its genomic structure defined by sequencing. The gene spans about 10 kb and consists of 12 exons. All splice sites conformed to the GT-AG motif and the exon-intron boundaries were largely conserved with other members of the P2X gene family so far cloned. A single transcription-starting site was identified by 5' RACE analysis, 233 bp upstream of the translation start site. The P2X(1) gene maps to the central region of mouse chromosome 11.

An immunostaining panel for diagnosis of malignancy in mucinous tumors of the pancreas

BACKGROUND

The diagnosis of malignancy in pancreatic mucinous cystic tumors depends on demonstrating invasion that may be focal and require extensive sectioning.

OBJECTIVE

To explore markers that may indicate malignant potential in mucinous cystic tumors.

DESIGN

Routinely processed sections from resected specimens of 12 normal pancreata, 14 pancreata with chronic pancreatitis, 9 mucinous cystic tumors, and 30 invasive adenocarcinomas were immunostained with antibodies to p53, HER-2/neu, epithelial growth factor receptor (EGFR), transforming growth factor alpha (TGF-alpha), and Ki-67.

RESULTS

Expression of p53, HER-2/neu, and Ki-67 was significantly more frequent in mucinous tumors than in normal pancreatic tissue and chronic pancreatitis tissue (P =.0003 to.05). Strong expression (more than one third of cells positive) and strong intensity (2+ and 3+) of staining of p53 and EGFR were seen only in carcinomas. Coexpression of p53/HER-2/neu and EGFR/HER-2/neu and a frequency of Ki-67+ nuclei of greater than 5% of cells discriminated between mucinous tumors and normal pancreatic tissue and chronic pancreatitis tissue. p53 expression was significantly more frequent in carcinomas than in mucinous tumor (P =.0326). Coexpression of p53/EGFR discriminated between mucinous tumors and carcinomas; however, TGF-alpha was not discriminative.

CONCLUSIONS

The immunostaining panel of p53, HER-2/neu, Ki-67, and EGFR can be helpful in indicating malignant potential in mucinous tumors of pancreas in routine pathology practice.

Development of fast purinergic transmission in the mouse vas deferens

ATP released by sympathetic varicosities of the mouse vas deferens binds to P2X receptors which activate fast, ligand-gated channels, resulting in depolarisation of smooth muscle cells. We examined the development of fast neuromuscular transmission at surface longitudinal smooth muscle fibres of the mouse vas deferens. Sympathetic varicosities were visualised using DiOC(2)(5)-fluorescence to aid in positioning loose patch electrodes over small sets of sympathetic varicosities to record the nerve terminal impulse (NTI) and excitatory junction currents (EJCs) evoked during nerve stimulation. At the earliest age at which EJCs could be detected, 21 days postnatal (PN), most recording sites rarely showed a detectable EJC over 100 trials, even though NTIs were recorded without failure. The extent of such intermittence in transmitter release progressively declined between 21 and 42 days PN. In addition, the mean amplitude of spontaneous EJCs (SEJCs) and EJCs increased by 2- and 2.4-fold, respectively, between 21 and 42 days PN. The rise time of EJCs varied widely at each age but declined with development (e.g., 7-14 ms at 28 days PN, 3-12 ms at 42 days PN). All EJCs were abolished by suramin (100 microM). Fast rise time EJCs were rapidly abolished by alpha,beta-methylene ATP (20 microM) while some (34%) of the slower rise time EJCs were resistant to rapid desensitisation of this kind. P2X(1) and P2X(2) mRNAs were detected by reverse transcription and polymerase chain reaction (RT-PCR) to determine whether levels of expression of the receptor subunits might explain the increased EJC amplitude. Between 10 and 42 days PN no marked change was observed in the P2X(2) receptor mRNA or beta-actin mRNA (control). In contrast, the intensity of the RT-PCR band for P2X(1) receptor showed a progressive approximately 4.3-fold developmental increase relative to the P2X(2) band. These observations suggest that both prejunctional and postjunctional mechanisms cause the maturation of fast purinergic junctional transmission at the longitudinal muscle of the mouse vas deferens between 21 and 42 days PN.

[High-performance liquid chromatography determination of histamine in nasal mucosa of guinea pig after post-column derivatization]

A rapid and simple method for determining histamine by post-column derivatization liquid chromatography with fluorescent detection was described. SCX weakly acidic cation exchange column was used as an analytical column. Histamine was eluted at 13 min 12 s by 40 mmol.L-1 of trisodium citrate (pH5.50) at flow rate of 1.0 ml.min-1. The recoveries of histamine ranged from 1.0 mumol.L-1 to 100 mumol.L-1 were above 92%. The detection limit for histamine was 50 nmol.L-1 and the linear range for histamine was 50 nmol.L(-1)-500 mumol.L-1.

N-Methyl-5-tert-butyltryptamine: A novel, highly potent 5-HT1D receptor agonist

It has been observed that reported 5-HT1D receptor agonists have at least one heteroatom (N, O, or S) on the 5-substituent of the indole. This has led to the hypothesis that a 5-substituent capable of participating in hydrogen bonding is critical for conveying high affinity. This article describes the synthesis and biological evaluation of a new series of 5-alkyltryptamine analogues, which does not have a heteroatom in the 5-substituent group. In contrast to the hypothesis, 5-alkyltryptamines all exhibit high binding affinities for the human 5-HT1D receptor. The size of the lipophilic alkyl group at the 5-position of the indole has significant impact on the 5-HT1D binding affinity. Compounds with a tert-butyl group at the 5-position such as 9d, 10, and 11 were identified. These analogues display high binding affinity (Ki < 1 nM) and moderate receptor selectivity in comparison with known antimigraine agents such as sumatriptan, naratriptan, rizatriptan, and VML-251.

Trace element content in drinking water of nasopharyngeal carcinoma patients

Chinese in the Xiangxi region of Hunan province in China have a high incidence of nasopharyngeal carcinoma (NPC). For analyzing the relation between NPC and trace elements, the concentrations of 7 trace elements in drinking water (well water) of high- and low-incidence areas were measured (75 samples). The results showed that the concentrations of Ni, Zn and Cd in drinking water of high-incidence areas were significantly higher than those in low-incidence areas. Especially, the Ni level in drinking water had a significant positive correlation with NPC mortality. These observations are consistent with earlier studies. We also found a highly positive correlation between Ni/pH value in drinking water and NPC mortality. This suggests that only considering the ion concentration in drinking water is not enough, we should also pay attention to the pH of the drinking water when we study the relation between NPC and trace elements. Because the pH of the medium can strongly affect trace element chemical characteristics and its metabolic state in living systems, the M/pH (M, metal concentration) may be an important factor worthy of further research.